The present invention relates to a method of segmentation and recognition of patterns and, more particularly, to a method of segmentation and recognition of relaxed handwritten character patterns for use in an optical character reader (OCR).
Conventionally, when an optical character reader (OCR) is used to read handwritten characters, it is required that each character be written correctly within a character frame 11 as shown in FIG. 1(a). The tolerance of over-framing is 1.0-1.5 mm in the vertical direction and sufficiently small as not to jut out into the adjacent frame in the horizontal direction, as shown in FIG. 1(b).
In order to make optical character readers more attractive to the user, it is necessary to free the writer from writing alphanumeric characters in frames peculiar to the OCR as mentioned above, and to allow the writer to write characters in a more relaxed style, as shown in FIGS. 2(a) and 2(b).
The conventional character frame has relatively large dimensions with an inter-frame gap 5 in the range of 0.5-1.0 mm, whereas the character frame used in the relaxed-style OCR system will have smaller dimensions as shown by 12 and 13 in FIGS. 2(a) and 2(b) and will have no inter-frame gap as shown by 6 and 7. As a result, characters may significantly jut out of the frame 12 or 13, and adjacent characters may overlap in the vertical direction or interlace with each other. In addition, when a character is written dividedly, like characters "5" and "M" shown in FIGS. 2(a) and 2(b), for example, a large part of the character may enter in the adjacent frame, posing a difficult problem for the OCR in reading characters. The prior art system cannot cope with these problems for segmenting and reading character patterns correctly.